This image, of what can possibly be called the supporting girls of K-ON!, is remarkable not so much for its quality (which it certainly possesses), but that it is actually fanart by a Pixiv artist, and not actually an official picture.
All the girls look excellent, with Ritsu and Sawa-chan’s exposed bellies likely being the best points on display. Nodoka’s megane and inappropriately heavy clothing look as moe as ever.
The lack of detail on Tsumugi’s shorts may be the picture’s weakest link, but at least she a moe ponytail on to make up for it.
For an amusing gag, quickly compare the fanmade image above to the (official) recent Megami magazine poster of the rest of the show’s cast shown below, and wonder if you would have realized that you were not looking at two official pictures?
The talented Pixiv artist, Kumosuke, apparently had the above Megami picture in mind when drawing her own complementary image, which she teasingly named “The Four Unpopular Ones.”
Kumosuke also has this maid-filled picture to her credit:
More of her art is available at his Pixiv profile.